A method for preparing cyclic carbonates

Abstract

This invention discloses a method for preparing cyclic carbonates, belonging to the field of small-molecule green catalysis. The method involves the catalytic reaction of epoxides with carbon dioxide to obtain the target product under the catalysis of a thionium salt-structured catalyst. This method offers high selectivity, high yield, short reaction time, and simple, low-cost catalyst synthesis, resulting in cyclic carbonates free of metal residues.

Description

Technical Field

[0001] This invention belongs to the field of green catalytic synthesis technology, specifically relating to a method for synthesizing five-membered cyclic carbonates. Background Technology

[0002] The rapid increase in atmospheric carbon dioxide concentration has triggered a series of problems, including sea-level rise and global warming. Therefore, reducing atmospheric carbon dioxide concentration is crucial. Current methods for reducing atmospheric carbon dioxide levels include physical absorption and storage, biological utilization, and chemical capture and conversion. As a green, inexpensive, and renewable C1 resource, converting carbon dioxide into high-value-added products is of great significance in industrial applications. Conversion methods include reduction and addition strategies. Reduction methods involve hydrosilylation (Green Chem., 2017, 19, 5614-5624), which involves reacting carbon dioxide with amine compounds in the presence of a catalyst to produce carbamates. Since carbon in carbon dioxide is in its highest oxidation state and possesses thermodynamic and kinetic stability, substrates with higher inherent energy (such as epoxides) are typically required for the reaction. Therefore, addition strategies mainly involve the cycloaddition reaction of epoxides with carbon dioxide to generate high-value-added cyclic carbonates.

[0003] The resulting organic cyclic carbonates can be used as intermediates in fine chemical synthesis, such as oxazolidinones (Org. Lett. 2018, 20, 5036-5039), or directly as solvents (Chem. Rev., 2010, 110, 4554-4581). Alternatively, the functional groups of cyclic carbonates can be diversified to become poly(hydroxyl polyurethane) (Rapid. Commun. 2014, 35, 1238-1254) and polycarbonate (Green Chem. 2019, 21, 406-448) as the main materials for liquid and solid electrolyte batteries (Electrochem. Commun. 2017, 77, 58-61).

[0004] Currently, the reported catalyst types for the cycloaddition reaction of carbon dioxide with epoxides to produce cyclic carbonates are mainly organic catalysts and metal catalysts. Metal catalysts primarily involve various metal complexes, such as zinc (Tetrahedron Lett., 2004, 45, 8307-8310), cobalt (Dalton Trans., 2018, 47, 1768-1771), and aluminum (ACS Catal., 2015, 5, 3398-3402). Although these metal catalysts exhibit high activity, the final cyclic carbonate product may contain metal residues, limiting their industrial application. Organic catalysts such as nitrogen-containing cyclic phosphorus compounds, ionic liquids (Adv. Synth. Catal., 2010, 352, 2233), nitrogen-containing cyclic carbenes, pyridinium salts (Green Chem., 2009, 11, 1876), and phenolic catalysts (Eur. J. Org. Chem., 2004, 3080-3089) produce cyclic carbonate products with no metal residues and high yields and selectivity. However, these catalysts or raw materials are expensive, or the purification process is complex, and high pressure or high temperature conditions are generally required for carbon dioxide fixation, which limits their widespread production and application. Therefore, finding efficient and stable organic catalysts for the fixation of carbon dioxide by epoxides remains one of the challenges facing the chemical industry. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a catalyst for the synthesis of cyclic sulfides and bromoalkyl acids, which in turn catalyzes the fixation of carbon dioxide by epoxides. The catalyst used in this method is metal-free, can be synthesized in one step, has good chemical stability and higher catalytic efficiency, and avoids metal residues caused by metal catalysts. It has great application potential in fields such as biomedicine.

[0006] The technical solution to achieve the above objectives is as follows:

[0007] A method for preparing a carbonate as shown in formula (III) involves reacting an epoxide as shown in formula (I) with carbon dioxide in the presence of a catalyst as shown in formula (II), wherein the catalyst is a thionium salt. The general reaction formula is as follows:

[0008]

[0009] Where R 1 R 2 Selected from hydrogen, branched or straight-chain alkyl groups with 1-4 carbon atoms, chloromethyl or R 3 -O-CH2 where R 3The R is selected from phenyl, phenyl substituted with an alkyl group of 1 to 3 carbon atoms, allyl, or branched or straight-chain alkyl groups of 1 to 4 carbon atoms. 1 R 2 The structures can be the same or different. In formula (II), m is 1 or 2, n is 1, 2, or 3, and X is Cl, Br, or I.

[0010] The preferred R 1 R 2 Selected from hydrogen, n-butyl, chloromethyl, phenyl, tolyl, R 3 -O-CH2-, the R 3 Selected from phenyl, tolyl, allyl, tert-butyl, or methyl. The R... 1 R 2 They can be the same or different structures.

[0011] This invention provides a method for preparing a thionium salt catalyst, wherein a cyclic sulfide as shown in formula (Ⅳ) and a bromoalkyl acid as shown in formula (Ⅴ) are refluxed in acetonitrile at 80°C for 3-8 h to obtain a crude product, which is then post-treated to obtain a catalyst as shown in formula (Ⅱ).

[0012]

[0013] Where n = 1, 2, 3, and m = 1 or 2.

[0014] The preferred catalyst as shown in formula (II) has the following structure:

[0015]

[0016] The epoxide is selected from the following structures:

[0017]

[0018] The preferred reaction temperature is 80℃-120℃.

[0019] The reaction temperature is further optimized to be 100℃.

[0020] Preferably, the pressure of the carbon dioxide is 0.1 MPa-2 MPa.

[0021] The pressure of carbon dioxide is further preferred to be 1 MPa.

[0022] Preferably, the molar ratio of the epoxide to the catalyst is 1:0.1-100:1. More preferably, the molar ratio of the epoxide to the catalyst is 1:0.05.

[0023] The preferred reaction time is 1-24 hours.

[0024] The optimal reaction time was 6 hours.

[0025] The preferred molar ratio of the (Ⅳ) cyclic sulfide to the (Ⅴ) bromoalkyl acid is 1:1 to 1.1:1.

[0026] Beneficial effects

[0027] The technical solution of the present invention has the following beneficial effects:

[0028] (1) The thioonium salt catalyst used in this invention has high activity and can produce cyclic carbonates within 6 hours, with a selectivity of 80%-99%.

[0029] (2) The raw materials for the catalyst in this invention are cheap and readily available, and the synthesis steps are simple, which is economically beneficial.

[0030] (3) The reaction conditions of the thioonium salt catalyst system are mild and there is no metal residue, which is in line with the green development strategy.

[0031] (4) This invention is the first to apply thioonium salt catalysts to the catalytic fixation of carbon dioxide by epoxides.

[0032] (5) Thionium salt catalysts can catalyze a range of epoxide substrates, and the substrates are widely applicable.

[0033] In summary, this invention has significant advantages over other existing catalytic systems, including being mild, efficient, easy to prepare, and metal-free. Attached Figure Description

[0034] The embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein...

[0035] Figure 1 Example 1 Catalyst (1) 1 H NMR image

[0036] Figure 2 Example 1 Catalyst (1) 13 C NMR spectrum

[0037] Figure 3 Example 2 Catalyst (2) 1 H NMR image

[0038] Figure 4 Example 2 Catalyst (2) 13 C NMR spectrum

[0039] Figure 5 Example 3 Catalyst (3) 1 H NMR image

[0040] Figure 6 Example 3 Catalyst (3) 13 C NMR spectrum

[0041] Figure 7 Example 4 Catalyst (4) 1 H NMR image

[0042] Figure 8 Example 4 Catalyst (4) 13 C NMR spectrum

[0043] Figure 9 Example 5 Catalyst (5) 1 H NMR image

[0044] Figure 10 Example 5 Catalyst (5) 13 C NMR spectrum

[0045] Figure 11 Example 6 Catalyst (6) 1 H NMR image

[0046] Figure 12 Example 6 Catalyst (6) 13 C NMR spectrum

[0047] Figure 13 Example 15: Carbonate product 1 H NMR image

[0048] Figure 14 Example 16: Carbonate product 1 H NMR image

[0049] Figure 15 Example 17: Carbonate product 1 H NMR image

[0050] Figure 16 Example 18: Carbonate product 1 H NMR image

[0051] Figure 17 Example 19: Carbonate product 1 H NMR image

[0052] Figure 18 Example 20: Carbonate product 1 H NMR image

[0053] Figure 19 Example 21: Carbonate product 1 H NMR image

[0054] Figure 20 Example 23: Carbonate product 1 H NMR image Detailed Implementation

[0055] The present invention can be further illustrated by the following embodiments, which are for illustrative purposes only and not for limiting the invention. Any person skilled in the art will understand that these embodiments do not limit the invention in any way, and that appropriate modifications and data transformations can be made thereto without departing from the spirit and scope of the invention.

[0056] The 1H NMR spectra involved in the examples were measured using a Bruker Ascend TM-400 NMR spectrometer, and the deuterated reagents used were deuterated chloroform (CDCl3) and deuterated water (D2O).

[0057] All raw materials used in the following examples are commercially available.

[0058] In the following embodiments, the various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, devices, instruments, equipment, etc. used in the following embodiments are all commercially available.

[0059] The catalyst structure used in the examples is as follows:

[0060]

[0061] The epoxide structure used in the examples is as follows:

[0062]

[0063] Example 1:

[0064] A 250 mL three-necked flask and a spherical condenser were used for dehydration and deoxygenation. Under nitrogen protection and at room temperature, tetrahydrothiophene (1.32 mL, 15 mmol, 1.00 eq.) and bromoacetic acid (2.08 g, 15 mmol, 1.00 eq.) were added to 45 mL of acetonitrile and mixed until dissolved. After mixing, the mixture was heated to 80 °C and refluxed for 3-6 h. The reaction solution gradually developed a white precipitate from a clear state. Acetonitrile was removed by filtration, and the white solid was washed with diethyl ether to remove a small amount of attached impurities. After drying, the pure catalyst (1) was obtained as a white solid. 1 HNMR (400MHz, Deuterium Oxide) δ4.25 (s, 2H), 3.65–3.56 (m, 2H), 3.48 (dt, J = 12.2, 5.8Hz, 2H), 2.39–2.20 (m, 4H). 13 C NMR (101MHz, Deuterium Oxide) δ45.16, 43.36, 28.19.

[0065] Example 2:

[0066] Take a 250 mL three-necked flask and a spherical condenser to perform dehydration and deoxygenation operations. Under nitrogen protection, add tetrahydrothiophene (1.32 mL, 15 mmol, 1.00 eq.) and bromopropionic acid (2.29 g, 15 mmol, 1.00 eq.) to 45 mL of acetonitrile at room temperature and mix until dissolved. After mixing, heat to 80 °C and reflux for 6-8 h. The reaction solution changes from pale yellow to brown. Remove acetonitrile by rotary evaporation, add a small amount of methanol to dissolve the rotary evaporator, and then precipitate the crude product with a large amount of diethyl ether or ethyl acetate. After standing, a pale yellow solid is obtained. Filter to remove diethyl ether or ethyl acetate, wash the solid with acetonitrile, and dry to obtain a white solid, which is the pure catalyst (2). 1 H NMR (400MHz, Deuterium Oxide) δ3.61 (dt, J=13.2, 6.5Hz, 2H), 3.45 (dt, J=23.2, 6.6Hz, 4H), 2.98 (td, J=6.8, 1.1Hz, 2H), 2.41–2.21 (m, 4H). 13 C NMR (101MHz, Deuterium Oxide) δ44.32, 37.94, 29.71, 28.22.

[0067] Example 3:

[0068] Take a 250 mL three-necked flask and a spherical condenser to perform dehydration and deoxygenation operations. Under nitrogen protection, add tetrahydrothiophene (1.32 mL, 15 mmol, 1.00 eq.) and bromobutyric acid (2.51 g, 15 mmol, 1.00 eq.) to 45 mL acetonitrile at room temperature and mix until dissolved. After mixing, heat to 80 °C and reflux for 6-8 h. The reaction solution changes from pale yellow to brown to dark brown. Remove acetonitrile by rotary evaporation, add a small amount of methanol to dissolve the rotary evaporator, and then precipitate the crude product with a large amount of ethyl acetate. After standing, a brown solid is obtained. Filter to remove the solvent, wash the solid with ethyl acetate to remove the surface color, and dry to obtain a grayish-white solid, which is the pure catalyst (3). 1 H NMR (400MHz, Deuterium Oxide)δ3.57(dt,J=13.4,6.6Hz,2H),3.41(dt,J=12.4,6.0Hz,2H),3.27–3 .20(m,2H),2.59(t,J=7.0Hz,2H),2.40–2.21(m,4H),2.08(p,J=7.3Hz,2H). 13 CNMR(101MHz,Deuterium Oxide)δ43.14,41.04,31.71,28.18,19.97.

[0069] Example 4:

[0070] A 250 mL three-necked flask and a spherical condenser were used for dehydration and deoxygenation. Under nitrogen protection, cyclopentane sulfide (1.55 mL, 15 mmol, 1.00 eq.) and bromoacetic acid (2.08 g, 15 mmol, 1.00 eq.) were added to 45 mL of acetonitrile and mixed until dissolved. After mixing, the mixture was heated to 80 °C and refluxed for 3-6 h. The reaction solution gradually changed from a clear state to a white solid. Acetonitrile was removed by filtration, and the white solid was washed with diethyl ether to remove a small amount of attached impurities. After drying, the pure catalyst (4) was obtained as a white solid. 1 HNMR(400MHz,Deuterium Oxide)δ4.37(d,J=4.9Hz,2H),3.58–3.49(m,2H),3.26(ddd,J=12.8,9.1,3.1Hz,2H),2. 12(dtt,J=14.8,7.3,3.4Hz,2H),1.90(dtt,J=15.7,9.2,3.4Hz,2H),1.78–1.56(m,2H). 13 C NMR (101MHz, Deuterium Oxide) δ41.65,36.20,22.15,20.37.

[0071] Example 5:

[0072] Take a 250 mL three-necked flask and a spherical condenser for dehydration and deoxygenation. Under nitrogen protection, add 1.55 mL of cyclopentane sulfide (15 mmol, 1.00 eq.) and bromopropionic acid (2.29 g, 15 mmol, 1.00 eq.) to 45 mL of acetonitrile at room temperature and mix until dissolved. After mixing, heat to 80 °C and reflux for 6-8 h. The reaction solution changes from pale yellow to orange-yellow. Remove acetonitrile by rotary evaporation, add a small amount of methanol to dissolve the rotary evaporator, and then precipitate the crude product with a large amount of diethyl ether or ethyl acetate. After standing, a pale yellow solid is obtained. Filter to remove diethyl ether or ethyl acetate, wash the solid with acetonitrile, and dry to obtain a white solid, which is the pure catalyst (5). 1 H NMR (400MHz, Deuterium Oxide)δ3.55(t,J=6.8Hz,4H),3.23(ddd,J=12.7,9.1,3.1Hz,2H),2.99(t,J=6.7Hz,2H), 2.16(dtt,J=14.7,7.2,3.3Hz,2H),1.90(dtt,J=15.7,9.2,3.3Hz,2H),1.80–1.58(m,2H). 13 C NMR (101MHz, Deuterium Oxide) δ36.76, 34.48, 28.76, 22.16, 20.47.

[0073] Example 6:

[0074] A 250 mL three-necked flask and a spherical condenser were used for dehydration and deoxygenation. Under nitrogen protection, cyclopentane sulfide (1.55 mL, 15 mmol, 1.00 eq.) and bromobutyric acid (2.51 g, 15 mmol, 1.00 eq.) were added to 45 mL of acetonitrile and mixed until dissolved. After mixing, the mixture was heated to 80 °C and refluxed for 6-8 h. The reaction solution changed from pale yellow to brown. Acetonitrile was removed by rotary evaporation, a small amount of methanol was added to dissolve the rotary evaporator, and the crude product was precipitated with a large amount of ethyl acetate. After standing, a pale brown solid was obtained. The solvent was removed by suction filtration, and the solid was washed with ethyl acetate to remove the surface color. After drying, a white solid was obtained, which was the pure catalyst (6). The filtrate was concentrated under reduced pressure to obtain the pure catalyst (4). 1 H NMR (400MHz, Deuterium Oxide)δ3.56–3.47(m,2H),3.41–3.34(m,2H),3.17(ddd,J=12.9,9.4,3.1Hz,2H),2.59(t ,J=7.0Hz,2H),2.21–2.03(m,4H),1.88(dtt,J=15.8,9.4,3.3Hz,2H),1.80–1.56(m,2H). 13 C NMR (101MHz, Deuterium Oxide) δ37.84,35.92,31.84,22.21,20.35,18.77.

[0075] Example 7:

[0076] Catalyst 1 (0.0568 g, 0.25 mmol, 0.05 eq.) and epoxide A (0.57 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 12 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 7%, and the selectivity was 99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0077] Example 8:

[0078] Catalyst 2 (0.0603 g, 0.25 mmol, 0.05 eq.) and epoxide A (0.57 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 12 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 99%, and the selectivity was 88%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0079] Example 9:

[0080] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide A (0.57 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 12 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 99%, and the selectivity was 99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0081] Example 10:

[0082] Catalyst 4 (0.0603 g, 0.25 mmol, 0.05 eq.) and epoxide A (0.57 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 12 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 5%, and the selectivity was 99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0083] Example 11:

[0084] Catalyst 5 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide A (0.57 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 12 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 99%, and the selectivity was 92%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0085] Example 12:

[0086] Catalyst 6 (0.0671 g, 0.25 mmol, 0.05 eq.) and epoxide A (0.57 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 12 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 99%, and the selectivity was 96%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0087] Comparing the conversion rates of epoxides using catalysts with different structures in Examples 7-12, it was found that catalyst 3 had similar effects to catalysts 2, 5, and 6. However, catalysts 2 and 5, due to their relatively unstable structures, were more prone to losing α-hydrogen under high temperature or alkaline conditions, generating allyl acid and tetrahydrothiophene or cyclopentane sulfide. Therefore, catalysts 2 and 5 were not considered as optimal catalysts. Since cyclopentane sulfide is more expensive than tetrahydrothiophene, and given that their effects were similar, catalyst 3 was chosen as the optimal catalyst from an economic perspective to further study the reaction of cyclic carbonates. 1 H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0088] Example 13:

[0089] Catalyst 3 (0.0319 g, 0.125 mmol, 0.025 eq.) and epoxide A (0.57 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 12 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 40%, and the selectivity was 99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0090] Example 14:

[0091] Catalyst 3 (0.0128 g, 0.05 mmol, 0.01 eq.) and epoxide A (0.57 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 2 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 12 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 3%, and the selectivity was 99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0092] Example 15:

[0093] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide A (0.57 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 6 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 94%, and the selectivity was 93%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR (400MHz, Chloroform-d) δ7.45–7.39(m,3H),7.34(dd,J=7.4,2.4Hz,2H),5.66(t,J=8.0Hz,1H),4.78(t,J=8.4Hz,1H),4.31(t,J=8.2Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ154.94,135.83,129.66,129.17,78.01,71.17.

[0094] As can be seen from Examples 13-15, reducing the catalyst loading or increasing the reaction pressure does not result in a high conversion rate of epoxides, while keeping the catalyst loading constant (5 mmol%) and shortening the reaction time yields better results. Therefore, 6 h was chosen as the reaction time.

[0095] Example 16:

[0096] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide B (0.68 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 6 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 99%, and the selectivity was 90%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1H NMR(400MHz,Chloroform-d)δ7.35–7.28(m,2H),7.02(tt,J=7.5,1.1Hz,1H),6.94–6.8 8(m,2H),5.03(dddd,J=8.1,5.9,4.4,3.6Hz,1H),4.65–4.51(m,2H),4.27–4.12(m,2H). 13 C NMR (101MHz, Chloroform-d) δ129.86,122.18,114.75,67.01,66.41.

[0097] Example 17:

[0098] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide C (0.76 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 6 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 99%, and the selectivity was 99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR(400MHz,Chloroform-d)δ7.16(ddd,J=7.4,4.2,2.7Hz,2H),6.93(td,J=7.4,1.0Hz,1H),6.81–6.75(m,1H),5.05(d dt,J=8.6,5.5,3.3Hz,1H),4.66–4.55(m,2H),4.26(dd,J=10.6,3.6Hz,1H),4.13(dd,J=10.6,3.1Hz,1H),2.22(s,3H). 13 C NMR (101MHz, Chloroform-d) δ155.86,154.91,131.21,127.21,127.00,121.78,110.92,74.32,67.11,66.36,16.09.

[0099] Example 18:

[0100] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide D (0.59 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 6 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 99%, and the selectivity was 80%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR(400MHz,Chloroform-d)δ5.88–5.73(m,1H),5.29–5.08(m,2H),4.79(ddt,J=9.2,6.6,3.6Hz ,1H),4.52–4.40(m,1H),4.33(ddt,J=7.0,6.0,1.3Hz,1H),4.07–3.91(m,2H),3.70–3.49(m,2H). 13 C NMR (101MHz, Chloroform-d) δ155.07,133.72,117.65,75.19,72.41,68.83,66.21.

[0101] Example 19:

[0102] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide E (0.56 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 6 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 33%, and the selectivity was 99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1H NMR(400MHz,Chloroform-d)δ5.78(ddt,J=16.9,10.1,6.6Hz,1H),5.13–5.00(m,2H),4.72(qd,J=7.7,5.1Hz,1H),4.52(t, J=8.1Hz,1H),4.08(dd,J=8.5,7.2Hz,1H),2.34–2.12(m,2H),1.98–1.87(m,1H),1.77(dddd,J=14.0,8.7,7.0,5.1Hz,1H). 13 C NMR (101MHz, Chloroform-d) δ155.08,136.17,116.57,76.43,69.44,33.17,28.76.

[0103] Example 20:

[0104] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide F (0.71 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 6 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 65%, and the selectivity was 99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR (400MHz, Chloroform-d) δ4.80–4.71(m,1H),4.47(t,J=8.2Hz,1H),4.38(dd,J=8.3,5.8Hz,1H),3.64–3.49(m,2H),1.19(s,9H). 13 C NMR (101MHz, Chloroform-d) δ155.28,75.26,66.73,61.43,27.43.

[0105] Example 21:

[0106] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide G (0.39 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 6 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 98%, and the selectivity was 92%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR(400MHz,Chloroform-d)δ4.99(ddt,J=8.3,5.7,3.9Hz,1H),4.55(t,J=8.7Hz,1H), 4.33(dd,J=8.9,5.7Hz,1H), 3.80(dd,J=12.5,4.3Hz,1H), 3.69(dd,J=12.5,3.7Hz,1H). 13 CNMR(101MHz,Chloroform-d)δ154.51,74.48,66.86,44.18.

[0107] Example 22:

[0108] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide H (0.6 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 6 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 28%, and the selectivity was >99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate.

[0109] Example 23:

[0110] Catalyst 3 (0.0638 g, 0.25 mmol, 0.05 eq.) and epoxide I (0.45 ml, 5 mmol, 1 eq.) were added to a 10 ml stainless steel pressure reaction tube. The reaction tube was sealed, and the hollow part of the reaction tube was replaced with carbon dioxide three times. Then, carbon dioxide was introduced into the reaction tube to a pressure of 1 MPa, and the reaction tube was sealed again. The temperature was raised to 100 °C, and the reaction time was 6 h. After the reaction was completed, the reaction tube was cooled to 0 °C with an ice-water mixture to release the residual gas. The conversion rate of the epoxide in the reaction solution was determined by nuclear magnetic resonance quantification using mesitylene as an internal standard. The conversion rate was 91%, and the selectivity was 99%. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution containing the product was obtained. The solvent was removed by rotary evaporation, and the product was dried to obtain pure five-membered cyclic carbonate. 1 H NMR(400MHz,Chloroform-d)δ4.79(ddt,J=8.3,6.0,3.7Hz,1H),4.47(t,J=8.4Hz,1H),4.34(d d,J=8.4,6.1Hz,1H),3.62(dd,J=11.1,3.6Hz,1H),3.53(dd,J=11.1,3.8Hz,1H),3.39(s,3H). 13 C NMR (101MHz, Chloroform-d) δ155.07,75.13,71.52,66.24,59.68.

Claims

1. A method for preparing a cyclic carbonate as shown in formula (III), characterized in that, The epoxide shown in formula (I) reacts with carbon dioxide in the presence of a catalyst shown in formula (II) to obtain a cyclic carbonate shown in formula (III), wherein the catalyst shown in formula (II) is a thionium salt structure. The molar ratio of the epoxide shown in formula (I) to the catalyst of formula (II) is 1:0.1-100:

1. The epoxides shown in formula (I) are selected from the following structures: The catalyst shown in formula (II) is selected from the following structures:

2. The preparation method according to claim 1, characterized in that, Catalyst (II) shown is 3, and its equation for the catalytic cycloaddition reaction of epoxide with carbon dioxide is shown in the figure below:

3. The preparation method according to claim 1, characterized in that, The molar ratio of the epoxide shown in formula (Ⅰ) to the catalyst in formula (Ⅱ) is 1:0.

05.

4. The preparation method according to claim 1, characterized in that, The reaction temperature is 80-120℃, the reaction pressure of carbon dioxide is 0.1-2MPa, and the reaction time is 1-24h.

5. The preparation method according to claim 4, characterized in that, The reaction temperature was 100℃, the reaction pressure of carbon dioxide was 1MPa, and the reaction time was 6h.

6. The preparation method according to claim 1, characterized in that, The catalyst as shown in formula (II) is prepared by reacting the cyclic sulfide shown in formula (IV) with the bromoalkanoic acid shown in formula (V).

7. The preparation method according to claim 6, characterized in that, The molar ratio of the reaction of formula (Ⅳ) to formula (Ⅴ) is 1:1-1.1:

1.

8. The preparation method according to claim 6, characterized in that, The reaction temperature is 80℃ and the reaction time is 3-8h.

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